Return Value

If the runtime class loader cannot resolve a reference to an assembly, type, or resource, the corresponding events are raised to give the callback a chance to tell the runtime which assembly the referenced assembly, type, or resource is in. It is the responsibility of the ResolveEventHandler to return the assembly that resolves the type, assembly, or resource, or to return null if the assembly is not recognized. For more information, see Resolving Assembly Loads and the AppDomain.ResourceResolve, AppDomain.AssemblyResolve, and AppDomain.ReflectionOnlyAssemblyResolve events.

Important

Beginning with the .NET Framework 4, the System.ResolveEventHandler event is raised for all assemblies, including resource assemblies. In earlier versions, the event was not raised for resource assemblies. If the operating system is localized, the handler might be called multiple times: once for each culture in the fallback chain.